Imaging of autoradiographs reveals that heteroploid MCF7 breast cancer subpopulations distinguished by DNA ploidy show marked differences in their cell cycle kinetics and phase distributions. Nuclear distribution of estrogen receptors and response to estrogen and anti-estrogens is also heterogeneous and influenced overall by culture density and growth rate. Accordingly, It is the objective to investigate the distribution of estrophilin in the various phases of cell cycle of MCF7 ploidy subpopulations in relation to their cytokinetics and proliferative response to estrogen and anti-estrogens (Tamoxifen, Nafoxidine, CI-628). This will provide a basis for understanding differences in the proliferative pattern and hormone-dependency of ploidy subpopulations and the extent to which these are determined by levels of estrogen receptor and their cycle distribution. Thus one may gain insight into mechanisms which govern the ascendancy of specific ploidy subpopulations during tumor growth in relation to the acquisiton of hormone autonomy. Automated imaging methods have been developed for simultaneous determination of the Feulgen-stained DNA content and grain count of labeled and unlabeled cells in autoradiographs after 3H- and 14C-thymidine labeling. The analytic scheme permits evaluation of the frequencies and proliferative patterns of discrete subpopulations distinguished by DNA ploidy. Pre- and posttreatment kinetics will be determined for MCF7 subpopulations with respect to 1) their cycle phase distributions, 2) frequencies in the mixed population, 3) rates of cell turnover in S, G-2 and G-1, 4) cell flux at the G-1/S, S/G-2 and G-2/M phase boundaries, 5) and their frequencies in non-cycling compartments. The methodology is critical in resolving the frequency and cycle phase distribution of individual subpopulations in such heteroploid culture systems. Nuclear estrophilin will be quantitated densitometrically by imaging of the immunoperoxidase reaction product after staining with monoclonal antibody (ERICA). Cells mapped during receptor analysis will be destained and relocated in Feulgen stained autoradiographs for determination of DNA ploidy and cytokinetics. These studies provide a way of identifying hormone responsive and non-responsive subpopulations in relation to ploidy and estrogen receptor presence and for evaluating the effects of receptor modulation as a determinant of their ascendancy and cell cycle kinetics in asynchronously growing heteroploid cultures.